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 World's First Automotive Application of the Miller-Cycle Engine
 IRVINE, Calif., Jan. 6 /PRNewswire/ -- When the 1995 Mazda Millenia S luxury sedan goes on sale in the United States this spring, it will feature the company's innovative Miller-cycle engine, which allows a smaller engine to deliver the same performance as a larger one. This marks the first time this breakthrough engine technology has been used in a production automobile.
 The advanced 2.3-liter DOHC 24-valve V6 Miller-cycle engine develops 210 horsepower at 5,300 rpm and 210 pound-feet of torque at 3,500 rpm -- performance equivalent to a 3.3-liter engine. At the same time Mazda's Miller-cycle engine returns 10 percent to 15 percent better fuel efficiency than conventional engines of comparable performance. The Millenia S returns fuel economy figures of 20 mpg city/28 mpg highway, while its competitors with comparable performance return fuel economy figures in the 18 mpg city/24-26 mpg highway range. This improved fuel efficiency also reduces carbon dioxide emissions by the same amount.
 The Miller-Cycle Engine: How It Works
 The Millenia Miller-cycle engine's superb performance and fuel efficiency come through the use of a new combustion cycle. The Miller cycle was named for Ralph H. Miller, an American who pioneered the combination of compressing the intake charge and altering the valve timing to achieve higher output from less displacement.
 Conventional engines, known as Otto-cycle engines for German inventor Nicholas Otto, are characterized by four equal strokes during the combustion cycle: intake, compression, expansion, and exhaust. Because the length of each stroke is the same, the compression ratio equals the expansion ratio.
 Previously, in order to increase engine torque, one of two methods was available: increase engine displacement or force more air and fuel into the combustion chamber. Increasing displacement tends to result in reduced fuel efficiency since the energy consumed to run the engine itself increases in proportion to the size of the engine.
 Forcing more air into the combustion chamber can achieve the high volumetric efficiency and the drivability of a larger engine. However, in the case of Otto-cycle engines, when a large amount of air is pushed into the cylinders and compressed, the air in the cylinder increases in temperature and tends to produce abnormal combustion -- resulting in engine knocking or pinging. In order to prevent this undesirable effect, the compression ratio is lowered, which also lowers the expansion ratio. As a result, some of the benefits of forcing more air into the cylinder are lost, minimizing the effective energy conversion and limiting any fuel efficiency gains.
 The Miller-cycle engine delays the closing of the intake valves until after the piston has risen approximately one-fifth of its stroke. This reduces the effective compression ratio, thus reducing the possibility of abnormal combustion, while allowing the full expansion of the combustion gases in the cylinder, which maximizes its thermal efficiency.
 To fully realize the potential of the Miller-cycle engine, Mazda has added a Lysholm compressor to force large amounts of air into the cylinders. This application of a Lysholm compressor is the world's first in an automotive application and is the result of a joint development program between Mazda and IHI(a) in Japan.
 The belt-driven Lysholm compressor uses a unique screw-type rotor system to compress the intake air. This compressed air then travels into the intake manifold, where fuel is added via fuel injectors, and finally into the combustion chambers.
 As the piston begins its upward stroke, excess air returns to the intake manifold. However, because the intake system is pressurized to about 28.5 psi by the compressor, ample air required to produce 1.5 times more torque than a comparably sized engine can be kept in the cylinder. Since the practical compression ratio is low, the mixture in the combustion chamber is compressed and ignited, just as in a conventional engine.
 2.5-Liter DOHC V6 Also Offered
 While the Millenia S features the Miller-cycle engine, the Millenia offers a 2.5-liter DOHC 24-valve V6 engine that produces 170 horsepower at 5,800 rpm and 160 pound-feet of torque at 4,800 rpm. The engine features sequential multiport electronic fuel injection, hydraulic valve lash adjusters, and a lightweight aluminum alloy block with cast-in iron cylinder liners and main bearing supports.
 (a) Ishikawajima-harima Heavy Industries Co. Ltd.
 -0- 1/6/94
 /CONTACT: Fred Aikins, 800-248-0459 (in the U.S.) or 800-346-2286 (in California)/

CO: Mazda North America ST: California IN: AUT SU: PDT

NY-LS -- LA023 -- 9905 01/06/94 16:42 EST
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Publication:PR Newswire
Date:Jan 6, 1994

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